The US Securities and Exchange Commission has warned asset managers that coordinating their activities to influence companies could expose them to tougher disclosure requirements typically applied to activist investors, according to a report by the Financial Times.

The warning follows an SEC investigation into the role played by BlackRock, Vanguard and State Street in the 2021 campaign that resulted in three ExxonMobil directors being replaced after activist hedge fund Engine No1 launched a board challenge.

The regulator stopped short of taking enforcement action against the firms, but said it had “serious concerns” about the conduct of some asset managers involved in the Climate Action 100+ investor coalition. The SEC said fund groups should be cautious about similar coordinated activities or risk losing the regulatory treatment afforded to passive investors.

The distinction is significant for hedge funds and other investors seeking to influence corporate strategy. Asset managers that qualify as passive investors can generally report their holdings using the shorter Form 13G, while investors deemed to be acting as activists or as part of a coordinated group can face the more demanding Form 13D regime.

An SEC official said the investors involved in the Exxon campaign appeared to have come close to crossing the line separating passive investment from coordinated activism.

The commission said its report was intended as guidance for the market ahead of the 2027 proxy season, rather than as the basis for further enforcement action. The investigation focused on whether BlackRock and State Street, both CA100+ participants, along with Vanguard, had coordinated their voting and engagement activities in a manner that could constitute a formal investor group.

The issue could be particularly relevant to activist hedge funds, which increasingly work alongside institutional investors to build support for board changes, strategic reviews and other shareholder campaigns. The SEC's stance could make large passive managers more cautious about collaborating with activists, potentially affecting the ability of hedge funds to assemble voting support for campaigns.

BlackRock and State Street reportedly declined to comment, while Vanguard reportedly had not immediately responded to requests for comment.